554 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.42. 



axillars, and under wing-coverts, brownisli slate color, the longest 

 lower tail-coverts with paler edgings, the thighs exteriorly dark, 

 rufescent brown; edge of wing broadly creamy white. 



Measurements. — Male:^ Wing, 160-174.5 (average, 166) mm.; tail, 

 56-66 (60.7) ; exposed culmen, 54-60 (57.0) ; height of bill at base, 

 10.5-12 (11.0); tarsus, 44-49 (47.3); middle toe, 40-45 (42.8). 



Female:^ Wing, 157-169 (161.9) mm.; tail, 53-64 (59.3); exposed 

 culmen, 54-59 (56.2); height of bill at base, 10.7-12 (11.1); tarsus, 

 42.5-47 (45.3); middle toe, 40-43 (41.2). 



Type-locality.— SsLii Miguel Island, Pearl Islands, Bay of Panama, 

 Panama. 



Geographical distribution. — San Miguel Island, and probably also 

 other of the Pearl Islands, Bay of Panama, Panama. 



This Pearl Islands race differs in color from Butorides virescens 

 virescens as from Butorides virescens Tiypernotius, and in size even 

 more markedly. From Butorides virescens saiuratus it may be dis- 

 tinguished by its smaller size, lighter colors throughout, including 

 upper parts, tail, and edgings of superior wing-coverts; lighter, more 

 rufescent (less purplish) neck and sides of head. It resembles 

 Butorides virescens frazari, but is much smaller, with less deeply col- 

 ored posterior lower parts; lighter, more rufescent Gess purplish) 

 neck and sides of head, and differs otherwise as from Butorides 

 virescens Tiypernotius. 



The two Juvenal birds examined differ from the corresponding 

 plumage of Butorides virescens Tiypernotius in their paler, duller, more 

 grayish upper parts, and lighter streaks on lower surface. 



Messrs. Thayer and Bangs have already commented at length ^ on 

 the considerable individual variation in the series of birds from the 

 Pearl Islands. Notwithstanding this variation, these birds represent 

 a very distinct subspecies, as comparison of the series available 

 readily shows. The female averages somewhat smaller than the 

 male, chiefly in length of wing. 



In the above described * extreme adult plumage, Butorides virescens 

 margaritopTiilus curiously and closely resembles the adult of Butorides 

 hrunescens, from Cuba, but is somewhat less brownish on the posterior 

 lower surf ace ; has the edgings of superior wing-coverts much paler, 

 on greater coverts even whitish, and thus much more conspicuous; 

 and, most important of all, has always a broad and conspicuous white 

 edge to the wing, and at least an indication of the light median gular 

 and jugular stripe, which is entirely absent in Butorides hrunescens; 

 and the median part of throat as well as of chin trenchantly and con- 



1 Twelve specimens, from San Miguel Island, Pearl Islands, Panama. 



2 Nine specimens, from the same island. 



• Bull. Mus. Comp. Zool., vol. 46, No. 8, September, 1905, pp. 142-144. 



* See p. 553. 



